Thermostatic packaging

ABSTRACT

Arrangements and methods for thermostatic packaging are provided herein. In some embodiments, in response to a change in temperature, an endothermic or exothermic reaction can be initiated to counteract the change in temperature.

TECHNICAL FIELD

Embodiments provided herein relate generally to arrangements andapparatuses for thermostatic arrangements, and methods of maintainingand/or controlling a temperature.

BACKGROUND

A variety of technologies exist for controlling and/or regulating thetemperature of a storage space. Such technologies can be effective in anumber of ways. In some situations, a storage space can simply beisolated from its environment, such as with an ice chest, therebypassively regulating the temperature of the storage space. In othersituations, a more active temperature regulation can be achieved byemploying, for example, a thermostat and cooling system, such as used ina refrigerator.

SUMMARY

Some embodiments provided herein include a cooling system that includesa first reactant and a second reactant. In some embodiments, the firstreactant can endothermically react with the second reactant to absorbheat. In some embodiments, the cooling system can include atemperature-responsive divider positioned between at least some of thefirst reactant and at least some of the second reactant. In someembodiments, at a first temperature, the temperature-responsive divideris impermeable to the first reactant, the second reactant, or the firstreactant and the second reactant. In some embodiments, at a secondtemperature, the temperature-responsive divider is permeable to thefirst reactant, the second reactant, or the first reactant and thesecond reactant.

Some embodiments provided herein include a method of regulating atemperature. The method can include providing a cooling system. Thecooling system can include a first reactant, a second reactant, and atemperature-responsive divider. In some embodiments, the first reactantcan react endothermically with the second reactant. In some embodiments,the temperature-responsive divider positioned between at least a part ofthe first reactant from at least a part of the second reactant. Themethod can include changing a first conformation of thetemperature-responsive divider to a second conformation of thetemperature-responsive divider upon an increase in temperature, suchthat the second conformation permits the first reactant, the secondreactant, or the first and the second reactant to pass through thetemperature-responsive divider such that an endothermic reaction occurs.

Some embodiments provided herein include a packaging. The packaging caninclude a first reactant. The packaging can include a second reactant.The packaging can include a temperature-responsive divider positionedbetween at least some of the first reactant and at least some of thesecond reactant. In some embodiments, the first reactant canendothermically react with the second reactant to absorb heat. In someembodiments, at a first temperature, the temperature-responsive divideris impermeable to the first reactant, the second reactant, or the firstreactant and the second reactant. In some embodiments, at a secondtemperature, the temperature-responsive divider is permeable to thefirst reactant, the second reactant, or the first reactant and thesecond reactant.

Some embodiments provided herein include a method of preparing a coolingsystem. The method can include providing a first reactant and providinga second reactant, such that the first reactant can endothermicallyreact with the second reactant to absorb heat. The method can includeproviding a temperature-responsive divider positioned between at leastsome of the first reactant and at least some of the second reactant. Insome embodiments, at a first temperature, the temperature-responsivedivider is impermeable to the first reactant, the second reactant, orthe first reactant and the second reactant. In some embodiments, at asecond temperature, the temperature-responsive divider is permeable tothe first reactant, the second reactant, or the first reactant and thesecond reactant.

In some embodiments, any one or more of the endothermic devices and/ormethods provided herein can be applied to an exothermic arrangement aswell, simply by swapping the first and second reactants for reactantsthat produce an exothermic reaction.

In some embodiments, a heating system is provided. The heating systemcan include a first reactant and a second reactant. The first reactantcan exothermically react with the second reactant to emit heat. Thesystem can include a temperature-responsive divider positioned betweenat least some of the first reactant and at least some of the secondreactant. At a first temperature, the temperature-responsive divider isimpermeable to the first reactant, the second reactant, or the firstreactant and the second reactant. At a second temperature, thetemperature-responsive divider is permeable to the first reactant, thesecond reactant, or the first reactant and the second reactant.

In some embodiments a method of regulating a temperature is provided.The method can include providing a heating system. The heating systemcan include a first reactant and a second reactant, wherein the firstreactant can react exothermically with the second reactant. The systemcan include a temperature-responsive divider positioned between at leasta part of the first reactant from at least a part of the secondreactant. The method can further include changing a first conformationof the temperature-responsive divider to a second conformation of thetemperature-responsive divider upon a decrease in temperature. Thesecond conformation permits the first reactant, the second reactant, orthe first and the second reactant to pass through thetemperature-responsive divider such that an exothermic reaction occurs.

In some embodiments a packaging is provided and includes a firstreactant and a second reactant. The first reactant can exothermicallyreact with the second reactant to emit heat. A temperature-responsivedivider can be positioned between at least some of the first reactantand at least some of the second reactant. At a first temperature, thetemperature-responsive divider is impermeable to the first reactant, thesecond reactant, or the first reactant and the second reactant. At asecond temperature, the temperature-responsive divider is permeable tothe first reactant, the second reactant, or the first reactant and thesecond reactant.

In some embodiments a method of preparing a heating system is provided.The method can include providing a first reactant and providing a secondreactant. The first reactant can exothermically react with the secondreactant to emit heat. The method can include providing atemperature-responsive divider positioned between at least some of thefirst reactant and at least some of the second reactant. At a firsttemperature, the temperature-responsive divider is impermeable to thefirst reactant, the second reactant, or the first reactant and thesecond reactant. At a second temperature, the temperature-responsivedivider is permeable to the first reactant, the second reactant, or thefirst reactant and the second reactant.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates some embodiments of a thermostatic packaging.

FIG. 2 is a flow diagram illustrating some embodiments of a method ofregulating temperature.

FIG. 3 is a drawing illustrating some embodiments of atemperature-responsive divider.

FIG. 4 is a flow diagram illustrating some embodiments of a method ofpreparing a cooling system.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented herein. It will be readily understood that the aspects of thepresent disclosure, as generally described herein, and illustrated inthe Figures, can be arranged, substituted, combined, separated, anddesigned in a wide variety of different configurations, all of which areexplicitly contemplated herein.

Some embodiments provided herein relate to temperature regulation. Whilethere are a variety of technologies by which this can be achieved, someembodiments provided herein achieve temperature regulation by at leastinitially maintaining two or more reactants separate from one another.The two or more reactants are then combined in a temperature dependentmanner. In some embodiments, this can be achieved by separating the twoor more reactants by a temperature-responsive divider. The divider canopen and/or close in response to a change in heat (for example, anincrease in heat). The opening of the divider allows the two reactantsto mix, allowing for a subsequent heat altering reaction to occur. Forthe sake of simplicity, the bulk of the following description focuses onarrangements in which an increase in heat results in the opening of thetemperature-responsive divider, which in turn allows the two reactantsto interact and produce an endothermic reaction, which lowers the localtemperature. However, as outlined herein as well, in some embodiments,the device and/or methods can be arranged so as to provide an exothermicreaction and thereby provide an increase in temperature.

FIG. 1 illustrates some embodiments of a section of a thermostaticpackage 100 that can include aspects of the technology provided herein.The arrangement can include a first reactant 110 and a second reactant120. The first reactant can be separated from the second reactant by atemperature-responsive divider 130 that is effectively impermeable to atleast one of the two reactants at a first temperature. At a secondtemperature (either lower or higher than the first), thetemperature-responsive divider undergoes a change to form a permeabletemperature-responsive divider 135. The permeable temperature-responsivedivider is permeable to at least one of the reactants 135, such that thereactants interact at a reaction site 140. In some embodiments, thereaction at the reaction site 140 is endothermic. In some embodiments,the reaction at the reaction site 140 is exothermic.

In some embodiments, a temperature-responsive divider separates a pairof reactants from each other when the temperature is below a threshold,but permits the reactants to react with each other when the temperaturepasses above the threshold. In some embodiments, the divider can openmechanically, thus permitting a liquid or gel reactant to pass throughpores and/or holes in the temperature-responsive divider. In someembodiments, the hydrophobicity of the divider can change, thuspermitting a molecule to pass through depending upon the molecule'shydrophobic properties. Additional options for temperature-responsivedividers are discussed below.

In some embodiments, the first reactant is one that reacts with thesecond reactant to produce an endothermic reaction. In some embodiments,the first reactant is one that reacts with the second reactant toproduce an exothermic reaction.

In some embodiments, a temperature-responsive divider is positionedbetween some (or all) of the first reactant, and some (or all) of thesecond reactant.

In some embodiments, at a temperature within an acceptable range, thetemperature-responsive divider is effectively impermeable to the firstreactant, the second reactant, or both reactants, such that thereactants do not react with each other. However, at a temperatureoutside of the acceptable range (which can be any predetermined and/ordesired range), the temperature-responsive divider can be permeable toone or both of the first and second reactant, such that these reactantsreact and allow for the appropriate reaction to occur. The endo- orexothermicity of the reaction can return the temperature to theacceptable range.

In some embodiments, the method and/or device can be applied in athermostatic package. The thermostatic package can include any number ofarrangements of reactants and/or other parts. In some embodiments, thepackage can include a first reactant and a second reactant separated bya temperature-responsive divider. An object to be kept cool (or warm)can be placed within and/or adjacent to the packaging, allowing fortemperature regulation of the object. In some embodiments, the dividerseparates a solvent from the first and second reactants.

Some embodiments of the method of employing this technology can includeproviding an arrangement of thermostatic packaging as described hereinand changing a first, effectively sealed, conformation of atemperature-responsive divider to a second, permeable, conformation upona change in temperature, such that a pair of reactants as describedherein interact with each other, thus consuming (or producing) heat tocounteract the change of temperature that initially changed the state ofthe temperature-responsive divider.

FIG. 2 is a flow diagram illustrating some embodiments of a method ofregulating a temperature. The method can include providing a coolingsystem that includes a first reactant and a second reactant. Whenallowed, the first reactant can react endothermically (or alternatively,exothermically) with the second reactant, however, initially there is aclosed temperature-responsive divider positioned between at least a partof the first reactant from at least a part of the second reactant 200.The method includes changing a first conformation of thetemperature-responsive divider to a second conformation of thetemperature-responsive divider upon an increase (or decrease) intemperature. The the second conformation permits the first reactant, thesecond reactant, or the first and the second reactant to pass throughthe temperature-responsive divider such that an endothermic (orexothermic) reaction occurs 210. The resulting change in heat from theendothermic (or exothermic) reaction can then be used to cool (or heat)and volume of space and/or an object 220. As noted herein, the dividercan also be used to separate a solvent from one or both of the reactantsas well to the same ends.

One skilled in the art will appreciate that, for this and otherprocesses and methods disclosed herein, the functions performed in theprocesses and methods may be implemented in differing order.Furthermore, the outlined steps and operations are only provided asexamples, and some of the steps and operations may be optional, combinedinto fewer steps and operations, or expanded into additional steps andoperations without detracting from the essence of the disclosedembodiments.

In some embodiments, the method includes effectively separating thefirst reactant (and/or solvent) from the second reactant (and/orsolvent) at the first temperature. In some embodiments, all orsubstantially all of the first reactant (and/or solvent) is separatedfrom the second reactant (and/or solvent) at the first temperature. Insome embodiments, only a portion of the first reactant (and/or solvent)is separated from the second reactant, and/or only a portion of thesecond reactant (and/or solvent) is separated from the first reactant(and/or solvent) at the second temperature. Thus, in some embodiments,some basal level of cooling and/or heating can occur, and the change inconformation of the temperature-responsive divider merely increasesand/or decreases the extent of the cooling and/or heating by allowingfor more of the reactants to interact or less of the reactants tointeract. In some embodiments, the first reactant (and/or solvent) iscompletely separated from the second reactant (and/or solvent) by thetemperature-responsive divider until a change in temperature changes thetemperature-responsive divider to its reactant permeable state.

In some embodiments, the method can include changing the conformation ofthe temperature-responsive divider from a first configuration in whichthe reactants of a reactant pair are separated by the divider and do notmix (e.g. a “closed” configuration) to a second configuration in whichthe reactants of the reactant pair can mix (e.g. an “open”configuration).

In some embodiments, the temperature-responsive divider includes anexpandable sheet with slits that are effectively sealed to one or bothof the reactants. The method can include straining the expandable sheetso that at least one perforation opens at the slit. In some embodiments,strain can applied to one axis of the sheet. In some embodiments, strainis applied to two or more axes of the sheet.

In some embodiments, the conformation of the temperature-responsivedivider changes upon a decrease in the local temperature. In someembodiments, the conformation of the temperature-responsive divider ischanged when the local temperature is above or below a pre-determinedthreshold temperature. In some embodiments, for example embodiments inwhich the reactants are configured to act endothermically, theconformation of the divider changes to permit the reactants to mix whenthe local temperature exceeds the threshold temperature. In someembodiments, for example embodiments in which the reactants areconfigured to act exothermically, the conformation changes to permit thereactants to mix when the local temperature is below the thresholdtemperature. In some embodiments, the threshold temperature is about−10° C., −5° C., −1° C., 0° C., 1° C., 2° C., 3° C., 4° C., 5° C., 6°C., 7° C., 8° C., 9° C., 10° C., 11° C., 12° C., 13° C., 14° C., 15° C.,17° C., 20° C., 22° C., 25° C., 27° C., 30° C., 34° C., 37° C., 40° C.,45° C., or 50° C., including any range above any one of the precedingvalues and any range between any two of the preceding values. Thus, insome embodiments, when the temperature threshold is crossed, thetemperature-responsive divider changes conformation to allow the firstand/or second reactants to intermix, changing the local temperature backtowards its starting value and thereby maintaining a local temperaturewithin a desired range.

In some embodiments the method includes changing the local temperatureby at least about 0.5° C. in response to a change in local temperature,for example at least about 0.5° C., 1° C., 2° C., 3° C., 4° C., 5° C.,6° C., 7° C., 8° C., 9° C., 10° C., 11° C., 12° C., 13° C., 14° C., 15°C., 20° C., 30° C., 40° C., 50° C., 60° C., 70° C., 80° C., 90° C., or100° C., including any range between any two of the listed values. Insome embodiments, for example embodiments in which the reactants areselected to react endothermically, the change in temperature is anincrease. In some embodiments, for example embodiments in which thereactants are selected to react exothermically, the change intemperature is a decrease.

In some embodiments, the opening of the temperature-responsive divideris reversible. Accordingly, in some embodiments, the method includeschanging the conformation of the temperature-responsive divider from thesecond configuration (e.g. an “open” configuration) back to the firstconfiguration (e.g. a “closed” configuration). In some embodiments, theconformation is changed back when the temperature crossed the thresholdtemperature to its initial temperature.

In some embodiments, the method includes at least 2 cycles of changingthe conformation of the temperature-responsive divider from the secondconfiguration back to the first configuration, for example at leastabout 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 17, 20, 25, 30, 35, 40, 45,50, 60, 70, 80, 90, 100, 120, 150, 200, 300, 400, 500, or more cycles.In some embodiments, the temperature-responsive divider is capable ofchanging its conformation from the open to the closed and/or closed tothe open state any number of times, for example, at least about 2, 3, 4,5, 6, 7, 8, 9, 10, 12, 15, 17, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80,90, 100, 120, 150, 200, 300, 400, 500 or more cycles.

In some embodiments, the open state of the temperature-responsivedivider is maintained as long as the temperature exceeds a thresholdlevel. Thus, the reaction is allowed to occur for as long as required inorder to revert the local temperature to a level beneath (or above) thethreshold level. Thus, in some embodiments, the system and/or method canbe self-regulating so that excessive levels of cooling or heating by thesystem can be avoided and/or minimized.

In some embodiments, changing the first conformation of thetemperature-responsive divider to the second conformation includeschanging the conformation of a temperature-responsive actuator.

In some embodiments, changing the first conformation of thetemperature-responsive divider to the second conformation includeschanging at least a portion of the surface of a polymer of thetemperature-responsive divider from a hydrophilic state to a hydrophobicstate.

In some embodiments, any divider can be used as a temperature-responsivedivider, as long as the divider can transition between impermeable topermeable for one or more of the reactants, in response to a change intemperature. In some embodiments, the divider can transition back toimpermeable from its permeable state.

In some embodiments, a temperature-responsive divider prevents (orreduces or minimizes) reactants from reacting with each other at a firsttemperature, but allows the reactants to react with each other when thetemperature is at a different, second temperature. In some embodiments,for example embodiments in which the arrangement is configured to coolvia an endothermic reaction, the second temperature is greater than thefirst temperature. In some embodiments, for example embodiments in whichthe arrangement is configured to heat via an exothermic reaction, thesecond temperature is less than the first temperature.

In some embodiments, the temperature-responsive divider can bepositioned between at least a portion of one reactant and at least aportion of the other reactant. In some embodiments, thetemperature-responsive divider is positioned between all of onereactant, and all of the other reactant. In some embodiments, thetemperature-responsive divider is positioned between substantially allof one reactant, and substantially all of the other reactant. In someembodiments, the temperature-responsive divider is positioned betweensubstantially all of one reactant, and only a portion of the otherreactant. In some embodiments, the temperature-responsive divider ispositioned between only a portion of one reactant, and only a portion ofthe other reactant. In some embodiments, the temperature-responsivedivider is positioned between at least about 70% of each reactant, forexample, at least about 70%, 75%, 80%, 85%, 90%, 95%, 97%, 98%, 99%,99.5%, or 99.9% of each reactant, including any range above any one ofthe preceding values.

In some embodiments, the temperature-responsive divider prevents (orreduces or minimizes) the reactants from reacting with each other at thefirst temperature by being impermeable to one or more of the reactants.In some embodiments, for example embodiments in which each reactant is aliquid, the temperature-responsive divider is impermeable to bothreactants at the first temperature but is permeable to one or both atthe second temperature. In some embodiments, for example embodiments inwhich a first reactant is a liquid and a second reactant is a solid, thetemperature-responsive divider is impermeable to the first reactant atthe first temperature, but permeable at the second temperature. In someembodiments, for example embodiments in which each reactant is a solid,the temperature-responsive divider is impermeable to a solvent that candissolve one or more of the reactants at the first temperature, but ispermeable to the solvent at the second temperature. In some embodiments,a solvent can be used to regulate the reaction indirectly. For example,rather than controlling the physical interaction of the two reactants,in some embodiments, the two reactants can be combined in an inert form,for example as a dried solid mixture, whereby the addition of watersolvates both reactants into a form in which an exothermic or anendothermic reaction can occur. Thus, any of the embodiments providedherein can also be configured in a form where the two or more reactantsare already combined, but are inert, until a solvent is added. In suchembodiments, the solvent can be kept separated from the premixedreactants by the temperature-responsive divider, and thus, the openingof the temperature sensitive divider will allow for the solvent todissolve the two reactants and the appropriate change in heat to occur.

In some embodiments, for example embodiments in which the arrangement isconfigured to cool a product by initiating an endothermic reaction, thetemperature-responsive divider prevents reactants from interacting witheach other when the temperature is below a threshold temperature, butallows the reactants to interact with each other when the temperature isabove a threshold temperature. In some embodiments, for exampleembodiments in which the arrangement is configured to heat a product byinitiating an exothermic reaction, the temperature-responsive dividerprevents reactants from interacting with each other when the temperatureis above a threshold temperature, but allows the reactants to interactwith each other when the temperature is below a threshold temperature.

In some embodiments, the temperature-responsive divider allows thereactants to react with each other at the second temperature by beingpermeable to one or more of the reactants at the second temperature. Insome embodiments, for example embodiments in which each reactant is aliquid, the temperature-responsive divider allows the reactants to reactwith each other at the second temperature by being permeable to all ofthe reactants at the second temperature. In some embodiments, forexample embodiments in which the first reactant is a liquid and thesecond reactant is a solid or gel, the temperature-responsive dividerallows the reactants to react with each other at the second temperatureby being permeable to the first reactant. The temperature-responsivedivider can be made of any material, for example, rubber and/orelastomer.

Some embodiments of a temperature-responsive divider 300 are illustratedin FIG. 3. As shown in the left side of FIG. 3, the body 310 of thetemperature-responsive divider can include at least one perforation orslit 320, which is present in a first conformation of the divider 300.The perforation or slit does not allow, or only allows an insubstantialamount of, interaction between the reactants. Thus, the divider providesan effective barrier or device for separating the first and secondreactants. At a temperature that exceeds a threshold 350, the divideradopts a second conformation (right-hand side of FIG. 3). Thisconformational change can be spread throughout the body 310 of thedivider so that numerous holes 370 are opened up from the previousperforations or slits 320. In this arrangement, the holes allow for aninteraction between the reactants.

The perforations or slits/holes can be created and/or modulated in anynumber of ways. In some embodiments, the temperature-responsive dividercan include at least one temperature-responsive actuator 340 which canexist in a first conformation as shown on the left side of FIG. 3. Insome embodiments, the temperature-responsive divider can also include afixed end 330. The presence of the fixed end 330 and the actuator 340can provide for the opening of the slits 320 to the holes 370. In someembodiments, the actuator can be made from a temperature sensitivematerial, such as a memory metal. Thus, in some embodiments, the body ofthe divider need not be made of a temperature sensitive material, butcan be associated and/or controlled by a temperature sensitive material,such that a change in temperature, drives a change in conformation thatopens (or makes more open) the slits and/or perforations in the body 310of the divider 300. In some embodiments, the body itself can be madefrom the temperature sensitive material, and thus, a shift inconformation of the body can directly open a slit or perforation.

In some embodiments, at a temperature 360 that is below a threshold, thetemperature-responsive actuator can revert to the first conformation340, so that the divider and the perforations also revert to the firstconformation 320.

In some embodiments, the temperature-responsive divider includes anexpandable sheet that includes at least one perforation. In someembodiments, the perforation includes at least one of a slit, a hole, ora flap. The perforation can be effectively impermeable to at least onereactant when the expandable sheet is in a first conformation. In someembodiments, the expandable sheet can be stretched along an axis that isparallel or substantially parallel to the largest diameter of theperforation, thus pinching or squeezing the perforation into a closed orsubstantially closed conformation. The perforation can become permeableto the first reactant and/or the second reactant when the expandablesheet is relaxed along the same axis, which allows the perforation toopen.

In other embodiments, the opposite arrangement can be employed, namelythe expandable sheet can be sealed when in its resting state (notstretched) but when stretched or strained along an axis that isperpendicular or substantially perpendicular to the largest diameter ofthe perforation the perforation is pulled open by tensile force.

In some embodiments, the sheet includes two or more perforations, andeach of the perforations is positioned in substantially the sameorientation on the sheet. In some embodiments, the perforations of thesheet are substantially parallel to each other.

In some embodiments, the longest diameter of the perforation is at leastabout 0.1 micrometers, for example about 0.1, 1, 10, 20, 30, 40, 50, 60,80, 100, 120, 140, 160, 180, 200, 250, 300, 400, 500, 600, 700, 800,900, 1000, 1200, 1500, 1800, 2000, 2500, 3000, 4000, 5000, 6000, 7000,8000, or 9000 micrometers, including any range above any one of thepreceding values and any range between any two of the preceding values.

In some embodiments, the body of the divider includes at least about 2perforations, for example, at least about 2, 10, 20, 30, 40, 50, 60, 70,80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 2000, 3000,4000, 5000, 10,000, or 100,000 perforations, including any range aboveany one of the preceding values and any range between any two of thepreceding values. In some embodiments, the body of the divider includeperforations at a density of at least about 1 perforation per squarecentimeter, for example at least about 1, 2, 3, 4, 5, 5, 7, 8, 9, 10,11, 12, 13, 14, 15, 17, 20, 22, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90,100, 110, 120, 150, 180, 190, 200, 220, 250, 300, 400, 500 600, 700,800, 900, 1000, 10,000, 100,000, or 1,000,000 perforations per squarecentimeter, including any range above any one of the preceding valuesand any range between any two of the preceding values.

In some embodiments, the body of the divider includes at least one of arubber, a metal, or an elastomer material. In some embodiments, the bodyof the divider includes two or more of the listed materials. In someembodiments, the body of the divider includes at least one layer of afirst material, and at least one layer of a second listed material, forexample at least one layer of a rubber, and at least one layer of anelastomer.

In some embodiments, interaction of the reactants is controlled bymechanically positioning the expandable sheet in one conformation at afirst temperature, and a different conformation at a second temperature.In some embodiments, a temperature-responsive actuator controls theconformation of the expandable sheet. The temperature-responsiveactuator can be in tensile communication with the expandable sheet, suchthat the temperature-responsive actuator positions the expandable sheetin a first configuration at a first temperature, and a secondconfiguration at a second temperature. In some embodiments, for examplewhen the temperature-responsive divider is configured to permit anendothermic reaction at the second temperature, the second temperatureis greater than the first temperature. In some embodiments, for examplewhen the temperature-responsive divider is configured to permit anexothermic reaction at the second temperature, the second temperature isless than the first temperature. In some embodiments, thetemperature-responsive actuator positions the expandable sheet in astretched or strained conformation at a first temperature, and a relaxedconformation at a second temperature. Accordingly, in some embodiments,the temperature-responsive actuator permits at least one reactant topass through perforations in the expandable sheet at the secondtemperature, but not at the first temperature.

In some embodiments, the temperature-responsive actuator includes atleast one of a bimetal, a shape-memory metal alloy, and/or a shapememory polymer. In some embodiments, two or more temperature-responsiveactuators can be employed. As noted above, in some embodiments, theentire body of the temperature-responsive divider includes at least oneof a bimetal, a shape-memory metal alloy, and/or a shape memory polymer

In some embodiments, the temperature-responsive actuator includes abimetal. In some embodiments, the temperature-responsive actuator has afirst concavity at a first temperature, and a second, opposite concavityat a second temperature. The first concavity can conform the expandablesheet so that the perforations are in a closed position, while thesecond concavity can conform the expandable sheet so that theperforations are in an open position. FIG. 3 illustrates an exemplarytemperature-responsive actuator having an arched shape 340 at a firsttemperature or temperature range 360 so that the perforations are closed320, and a second, opposite concavity 345 at a second temperature ortemperature range 350 so that the perforations 370 are open.

In some embodiments, the temperature-responsive actuator includes ashape memory metal alloy. The shape memory metal alloy can be configuredto remember a first conformation at a first temperature, such that theexpandable sheet is in the corresponding first conformation, and theperforations in an open position. The shape memory metal alloy can beconfigured to remember a second conformation at a second temperature,such that the expandable sheet is in the corresponding secondconformation, and the perforations are in a closed position. In somesituations, a single shape memory metal alloy actuator may not generatesufficient force to position a large expandable sheet in a strained orstretched position. Accordingly, some embodiments include an array of atleast two or more shape memory metal alloy actuators, for example atleast about 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90,100, 200, 300, 400, 500, or 1000 shape memory metal alloy actuators, inwhich each actuator is in tensile communication with the expandablesheet.

In some embodiments, the temperature-responsive actuator includes ashape memory polymer. At least one surface of the expandable sheet canbe laminated in the shape memory polymer. In some embodiments, theexpandable sheet is configured so that the perforations are closed whenthe sheet is in a first, relaxed conformation, and open when the sheetis in a second, strained conformation (for example, strain perpendicularor substantially perpendicular to the longest diameter of theperforation to distort the perforation to an open state whenappropriate). The shape memory polymer can be configured to return toits shape at a second temperature, from any given shape at a firsttemperature. The shape memory polymer can be applied to the sheet suchthat the “remembered” or set shape applies strain to the sheet andforces the perforations to open. Accordingly, at a first temperature,the shape memory polymer closely conforms to the shape of the expandablesheet, and the sheet remains closed. However, at a second temperature,the shape memory polymer returns to its set shape and induces the sheetto a strained, open, configuration. In situations in which a shapememory metal alloys might not generate a large enough force to open alarge sized sheet, an array of many memory metal alloys can be used toachieve the same result. In some embodiments, shape memory metal alloymemorizes an o-shape above T_(set), and is attached to all orsubstantially all of slit parts in FIG. 3.

In some embodiments, a shape memory polymer can be used as thetemperature-responsive divider without an additional mechanicalactuator. For example, a pore opening structure can be memorized aboveT_(set) and a rubber sheet having a relatively weak tension towards theclosed direction can be laminated with the shape memory polymer. Whenthe temperature rises beyond T_(set), the shape memory polymer startsreturning to the memorized shape, for example, the open hole state pullsagainst, and overcomes, the force generated from the laminated rubbersheet. When the temperature goes down below T_(set), the rubber layerpulls it back to the closed state.

Not all of the embodiments involve the opening and/or closing ofperforations. In some embodiments, the temperature-responsive dividerincludes a polymer membrane. A portion, substantially all, or all of asurface of the polymer membrane can be hydrophilic at the firsttemperature. That portion can be hydrophilic at a second temperature. Insome embodiments, the second temperature is greater than the firsttemperature. In some embodiments, the polymer is porous. In someembodiments, the polymer includes a temperature-responsive hydrogel. Insome embodiments, the polymer can absorb moisture when its surface (orportion thereof) is in a hydrophilic state, and can release moisturewhen it surface (or portion thereof) is in a hydrophobic state. Thus,the polymer can permit permeation of a reactant (or solvent) in aqueoussolution via capillary action when in the hydrophilic state, whileprohibiting permeation in the hydrophobic state. In some embodiments,the polymer can absorb a non-polar solution when its surface (or portionthereof) is in a hydrophobic state, and can release the non-polarsolution when it surface (or portion thereof) is in a hydrophilic state.Thus, the polymer can permit permeation of a reactant (or solvent) innon-polar solution.

Thus, rather than employing a gross hole that is opened or closed, someembodiments employ a class of polymers that change the surfacecharacteristic from hydrophilic to hydrophobic with temperature change,for example, N-isopropyl acryl amide. Thermo responsiveness of this typeof polymer can be controlled by the combination of copolymer compositionwith N-isopropyl acryl amide or N-alkyl acryl amide. For example, acopolymer of N-isopropyl acryl amide with diacetone acryl amide, acrylicacid and methylene-bis-acryl amide can be used to form atemperature-responsive hydro gel composition which works between 10degrees Centigrade and 40 degrees Centigrade.

In some embodiments, a porous membrane that includes such a polymer canbe used as a temperature-responsive divider. Such a polymer can behydrophilic at T_(set) and absorbs moisture to stop permeation. It canchange its surface property to hydrophobic above T_(set), and canrelease moisture from the membrane. In some embodiments, a micro porouslayer can generate a capillary effect to assist permeation of a reactantinto the other reactant. In some embodiments one of the reactants can beattached and/or laminated to the side of the temperature-responsivedivider. Such an arrangement can allow the attached and/or laminatedreactant to pull liquid from the other side when the divider opens athigher temperature.

In some embodiments, the polymer includes N-alkyl acryl amide. In someembodiments, the polymer includes N-isopropyl acryl amide. In someembodiments, the polymer includes a copolymer of N-alkyl acryl amide andN-isopropyl acryl amide. Without being bound by any one theory, theresponsiveness of the polymer can depend on the ratio of alkyl acrylamide and N-isopropyl acryl amide. In some embodiments, the ratio(weight to weight) of alkyl acryl amide to N-isopropyl acryl amide isabout 100:1, 70:1, 50:1, 40:1, 30:1, 20:1, 15:1, 10:1, 7:1, 5:1, 4:1,3:1, 2:1, 1:1, 1:2, 1:3, 1:4, 1:5, 1:7, 1:10, 1:20, 1:30, 1:40, 1:50, or1:100, including ranges between any two of the listed values. In someembodiments, the polymer includes a copolymer of N-alkyl acryl amide,di-acetone acryl amide, acrylic acid, and/or methylene-bis-acryl amide.

In some embodiments, the temperature-responsive divider can change to aconfiguration that is impermeable to the first reactant, the secondreactant, or the first and second reactant upon a return of thetemperature-responsive divider to the first temperature. In someembodiments, returning the divider to the impermeable configurationincludes closing perforations of an expandable sheet of the divider. Insome embodiments, returning the divider to the impermeable configurationincludes changing the hydrophobicity of the sheet. In some embodiments,even after the closure of the divider, some amount of the reactionand/or reactants can still be occurring and/or present together.

In some embodiments, one reactant, or a portion of that reactant ispositioned on one side of the temperature-responsive divider, while theother reactant, or a portion of the other reactant, is positioned onanother side of the temperature-responsive divider. In some embodiments,for example embodiments in which each reactant is a solid that issoluble in a solvent, both reactants are positioned on the same side ofthe temperature-responsive divider, and the solvent is positioned on adifferent side of the temperature-responsive divider. In someembodiments, the solvent is positioned on a side of thetemperature-responsive divider that is opposite the side on which thereactants are positioned.

The selection of the various reactants will depend upon the particularapplication. In some embodiments, two or more reactants can be selectedso that the reaction of the reactants has a cooling (or heating) effectthat counteracts a change in temperature within the packaging. Thus, insome embodiments, the reactants can react endothermically with eachother. The endothermic reaction can absorb heat. Pairs of reactants thatcan react endothermically with each other can include, but are notlimited to H₂O/NH₄NO₃, H₂O/NH₄Cl, NH₄NO₃/Urea, H₂O/Urea, H₂O/Ba(NO₃)₂,citric acid/sodium bicarbonate, H₂O/Xylitol, and H₂O/Erythritol. In someembodiments, the reactant pair is selected from Table 1 provided in theExamples. Some embodiments include two reactants that reactendothermically with each other when combined. Some embodiments includethree or more reactants that react endothermically when at least two ofthe reactants are combined, for example H₂O, NH₄NO₃, and NH₄Cl. Someembodiments include reactants that react exothermically with each otherwhen combined. Some embodiments include a catalyst.

The phase of the reactants under the conditions at which the endothermic(or exothermic) reaction begins can impact the ability of the reactantsto mix with each other and/or react. For example, if each of a pair ofreactants is a liquid at the temperature and pressure at which thetemperature-responsive divider allows the reaction to initiate, thereactants can readily intermix. Accordingly, in some embodiments, eachof the reactants is a liquid. In some embodiments, for exampleembodiments in which a gradual intermixing of the reactants isdesirable, each of the reactants is a gel, for example a hydrogel. Insome embodiments, one reactant is a liquid, and the other reactant is agel. In some embodiments, one reactant is a liquid, while the otherreactant is a solid. In some embodiments, one reactant is a gel, whilethe other reactant is a solid. In some embodiments, each reactant is asolid that is soluble in a solvent, and beyond the thresholdtemperature, the temperature-responsive divider allows a solvent toenter into one or more of the areas holding one or more of the reactantsand dissolve one or more of the reactants, thus allowing the reactantsto combine.

Optionally, a liquid or gel-phase reactant can be stored in a poroussubstrate. Thus, in some embodiments, a liquid or gel-phase reactant isstored in a porous sponge-like substrate, or a superabsorbent polymer,for example sodium polyacrylate. In some embodiments the liquid orgel-phase reactant is contained in a sponge-like substrate.

A solid reactant can react more rapidly if it has a relatively largesurface area. Thus, in some embodiments, the solid-phase reactant orreactants include at least one of a fiber, a bead, a powder, or agranular substance. In some embodiments, the solid-phase reactant isfixed onto a high-surface area substrate, for example activatedcharcoal, porous aluminum, silicate beads, or the like. In someembodiments, the solid-phase reactant includes xylitol, and is fixedonto calcium silicate, for example to form xylitol-fixed beads.

In some embodiments, the system includes one or more compartments forthe reactants. In some embodiments, the system includes a firstcompartment configured to contain the first reactant, and a secondcompartment to contain the second reactant. At least a portion of eachcompartment is defined by the temperature-responsive divider. In otherwords, the compartments are at least partially separated from oneanother by the divider. For example, a first surface of thetemperature-responsive divider can provide a surface of the firstcompartment, while a second surface of the temperature-responsivedivider can provide a surface of the second compartment. In someembodiments, the first surface can be opposite the second surface. Insome embodiments, the system includes two or more compartments for oneof the reactants. In some embodiments, system includes two or morecompartments for each of the reactants. In some embodiments, acompartment includes at least one of a sack, a box, a drum, a pouch, atube, a hopper, or a reservoir. In some embodiments, a compartment has avolume of at least about 0.001 liter, for example at least about 0.001,0.01, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 20, 30, 40, 50, 100, or 1,000 liters or more, including any rangebetween any two of the preceding values and any range above any one ofthe preceding values.

In some embodiments, the first compartment and second compartment areadjacent to each other. In some embodiments, the first compartment andsecond compartment are not adjacent, but are in fluid communication witheach other. In some embodiments, the first compartment is positionedpartially or wholly within the second compartment. In some embodiments,the first compartment is configured to contain the first reactant, andalso contains a plurality of second compartments, for example at leastabout 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 30, 40, 50, 70, 100, 200, 300,400, 500, 600, 700, 800, 900, 1000, 1200, 1500, 2000, 2500, 3000, 4000,5000, 6000, 7000, 8000, or 9000 second compartments, in which eachsecond compartment is a vesicle that includes at least one surface thatis defined by a temperature-responsive divider. In some embodiments,each of the plurality of dividers has the same temperature dependencefor opening and/or closing. In some embodiments, the temperaturedependence for opening and/or closing the different dividers can bedifferent, so that finer degrees of temperature control can bemaintained. In some embodiments, the temperature dependence for openingand/or closing the different dividers can be different, so that higherranges of temperature control can be obtained. For example, in someembodiments, a first divider will open if the temperature exceeds 30degrees Centigrade, and a second divider will open if the temperatureexceeds 40 degrees Centigrade and a third divider will open if thetemperature exceeds 50 degrees Centigrade. In some embodiments, thevarious reactants on each side of the different dividers can be set sothat a stronger (for example, more endothermic reaction) will occur foreach of the higher temperature dividers. Thus, in some embodiments, thereactant pair can be matched to the temperature-responsive divider sothat opening the divider will allow for a sufficiently endothermicreaction (or exothermic reaction) to occur to return the localenvironment to the desired temperature, from a temperature sufficient toopen the temperature-responsive divider.

In some embodiments, the arrangement includes a storage compartment. Thestorage compartment can be configured to contain at least one product tobe stored. In some embodiments, the storage compartment is configured tocontain at least about 2 products to be stored, for example at leastabout 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90,100, 120, 150, 180, 200, 300, 400, 500, or 1000 products to be stored.In some embodiments, the storage compartment is disposed adjacent to thefirst reactant, the second reactant, or both. In some embodiments, thestorage compartment is partially or wholly surrounded by the firstreactant, the second reactant, or both. In some embodiments, the storagecompartment is not adjacent to the first or second reactant, but is inthermal communication with the first or second reactant via a thermallyconductive material. The storage compartment can be made of any materialthat will allow an adequate transmission of heat and/or cold from thearea of the reaction to the volume of space contained by the storagecompartment. In some embodiments, the storage compartment can be madefrom metal, plastic, various polymers, ceramic, etc. In someembodiments, the storage compartment defines the local environment.Thus, in some embodiments, an increase (or decrease) in temperature inthe storage compartment is the change in temperature that drives theopening and/or closing of the temperature-responsive divider. In someembodiments, reaction that results then cools (or heats) at least partof the volume of the storage compartment. In some embodiments, thetemperature-responsive divider is in thermal communication with thestorage compartment.

Some embodiments employ the device and/or method as a package product.Such packaging can include any of the embodiments provided herein. Insome embodiments, the packaging includes the first reactant and thesecond reactant. The first reactant can endothermically react with thesecond reactant to absorb heat. The packaging can include thetemperature-responsive divider positioned between at least some of thefirst reactant and at least some of the second reactant. In someembodiments, at a first temperature the temperature-responsive divideris impermeable to the first reactant, the second reactant, or the firstreactant and the second reactant as described herein. At a secondtemperature, the temperature-responsive divider is permeable to thefirst reactant, the second reactant, or the first reactant and thesecond reactant. Of course, exothermic embodiments are also available asnoted herein.

There is no particular limitation on the forms in which the packagingcan be provided. In some embodiments, the packaging includes at leastone of a pouch, a wrap, a sack, an envelope, a box, a chest, a tray, acarton, a bag, or a shipping container. In some embodiments, thepackaging includes at least one compartment as described herein. In someembodiments, the packaging is a passive package, and does not requirethe use of electricity. In some embodiments, the packaging is oneconfigured for shipment. In some embodiments, the packaging is designedto hold or contain food. In some embodiments, the packaging is designedfor long-term storage of a product. In some embodiments, the packagingis designed for storing a pharmaceutical product.

Some embodiments include methods of preparing a cooling system.Embodiments of such a method are generally outlined in FIG. 4. Themethod can include providing a first reactant 400. The method canfurther include providing a second reactant as described herein, suchthat the reactants can endothermically (or exothermically) react witheach other 410. Of course, initially, the first and second reactants arenot undergoing a reaction, but are merely selected such that they arecapable of the relevant reaction when combined. The method can furtherinclude providing a temperature-responsive divider. The two reactantsare arranged such that they can interact when the temperature-responsivedivider is in its open state. Various options for their arrangement willdepend upon the particular state of the reactants and set up involved,as detailed herein. As outlined herein, in some embodiments, thetemperature-responsive divider separates at least a portion of the firstreactant from the second reactant at a first temperature, but at asecond temperature, the divider is permeable to the first reactant, thesecond reactant, or the first reactant and the second reactant 420.

In some embodiments, the system and/or method can provide a packageincluding two compartments which contain two different reactivechemicals separately in each compartment, a pair of chemicals that canreact with each other by endothermic (or exothermic) reaction; and atemperature-responsive divider separating the two compartments when thetemperature is low and breaking separation when the temperature risesabove the previously set temperature.

Example pairs of reactants are listed in Table 1. There are variousreactant pairs which react endothermically as listed in Table 1. Someembodiments can include any pair of reactants listed in Table 1. Bothxylitol-H₂O and erythritol-H₂O are appropriate around food products.

In some embodiments, reactant A is stored in a hydrogel form.Superabsorbent polymer such as sodium polyacrylates can be used to keepwater or a solution containing reactant A (of Table 1).

In some embodiments, any of the herein described systems and/or methodscan function without any external power supply or electricity. In someembodiments, the system structure is simple and need not employ a motor.In some embodiments, nontoxic and/or nonhazardous material combinations(such as the two reactants and the divider) can be employed. In someembodiments, all or substantially all of the parts are maturedmaterials. In some embodiments, the temperature sensing aspect of themethod or device operates to directly, physically, open a barrierbetween two reactants.

Examples 1-8 Cooling Arrangements

A polyethylene cylinder is divided into two compartments by atemperature-responsive divider. Each compartment has a volume of about 1liter. A reactant pair is provided, one reactant of the pair into eachof the two compartments, according to each of the pairings of Table 1.Thus, eight different reactant pairs are placed into eight differentcylinders.

TABLE 1 Exemplary Groups of Reactants Which Cause Endothermic ReactionAbsorbed Reactant Reactant heat No A B (kcal/mol) Additional Aspects 1H₂O NH₄NO₃ 6.08 2 H₂O NH₄Cl 3.73 3 NH₄NO₃ Urea 18.0 Ammonium Nitride isan optional material for non- food application. 4 H₂O Urea 3.7 5 H₂OBa(NO3)₂ 9.65 Optional material for non-food application. 6 CitricSodium CO₂ will be generated. acid Bicarbonate 7 H₂O Xylitol 35 kcal/gFood additives 8 H₂O Erythritol 43 kcal/g Food additives

The temperature-responsive divider includes a rubber sheet having asubstantially uniform thickness of about 5 mm. The rubber sheet includesperforations, each of which is a slit having a length of about 1 mm, andeach of which is in an effectively parallel orientation to the otherslits. The sheet contains the perforations at a density of about 10perforations per cm². The sheet includes a bimetallic actuator (as shownin FIG. 3). The bimetallic actuator is in tensile communication with thesheet along an axis substantially perpendicular to the longest axis ofthe perforations.

At temperatures of less than 5° C., the bimetallic actuator has aconcave configuration, and pushes the sheet against a fixed end, suchthat the sheet is compressed. The perforations stay closed, and thereactants do not react. At temperatures greater than 5° C., thebimetallic actuator adopts a convex configuration, and stretches thesheet from the fixed end. As the sheet is stretched, the slits open toholes, allowing the first and second reactants to mix and therebyallowing the endothermic reaction to occur.

When the endothermic reaction occurs, it will lower the localtemperature around the cylinders.

Example 9 Cooling Arrangement and Use Thereof

A pouch containing about 2 liters of NH₄NO₃ fixed onto silicate beads,is separated from a pouch containing 2 liters of H₂O by atemperature-responsive actuator. The pouch is wrapped around poultrycarcasses being transported. The temperature-responsive divider is madeof a copolymer of alkyl acryl amide and N-isopropyl acryl amide. Attemperatures below 2° C., the surface of the divider is hydrophobic, andsubstantially no water passes through. At temperatures above 2° C., thesurface of the divider is hydrophilic, and water can pass. The pouch andpoultry carcasses are initially at 1° C., and the surface of the dividerremains hydrophobic. During storage, the local temperature increasesfrom 1° C. to 4° C. The surface of the divider adopts a hydrophobicconfiguration, and water diffuses through the divider. The water reactsendothermically with the NH₄NO₃ and the local temperature decreases.When the local temperature is below 2° C. again, the divider surfacereturns to a hydrophobic configuration. Water stops diffusing throughthe divider, and the endothermic reaction ceases.

Example 10 Cooling Arrangement and Use Thereof

A double-walled chest contains an inner 5-liter compartment for storingdairy products. The chest also includes an intermediate space within thewalls of the chest that is filled with citric acid solid crystallinepellets and sodium bicarbonate pellets intermixed. Substantially nowater is present in the intermediate space. The outer wall containsvents for any CO₂ released by the reaction of sodium bicarbonate andcitric acid. A 2 liter reservoir of water is separated from theintermediate space containing citric acid and sodium bicarbonate by atemperature-responsive divider. The temperature-responsive dividerincludes a 3 mm-thick elastomer sheet, with 1 mm perforations at adensity of 2 perforations per cm². The sheet is laminated in shapememory polymer, which is programmed to remember (or revert to apreviously determined) shape at temperatures of 6° C. or greater. Thememory polymer is laminated onto the sheet so that in its memorized (orpreviously determined) conformation, the polymer stretches theperforations open. At temperatures of less than 6° C., the memorypolymer does not conform to its memorized shape, and elastic tension ofthe elastomer pulls the perforations shut.

The inner compartment is filled with cheese, at a local temperature of3° C. As the cheese is transported, the local temperature increases, andeventually increases from 3° C. to 7° C. When the temperature reaches 7°C., the shape memory polymer switches from its resting conformation (inwhich elastic tension of the sheet was sufficient to “pull” theperforations closed), to its memorized conformation (in which thetensile force of the polymer forces the perforations open). Theperforations open, allowing water to flow into the intermediatecompartment, and solubilize the citric acid, which reacts with sodiumbicarbonate endothermically. The endothermic reaction cools the cheeseproducts. CO₂ produced by the reaction is emitted through the vent.

Example 11 Heating Arrangements and Use Thereof

A container has an inner 5-liter compartment for storing heated foodproducts, and an intermediate space between the walls is filled with afirst exothermic reactant and a second exothermic reactant in dry form.Substantially no water is present in the intermediate space. A 0.5 literreservoir of water is separated from the intermediate space by atemperature-responsive divider. The temperature-responsive dividerincludes a 3 mm-thick elastomer sheet, with 1 mm perforations at adensity of 2 perforations per cm². The sheet is laminated in shapememory polymer, which is programmed to remember its shape attemperatures of 20° C. or lower. The memory polymer is laminated ontothe sheet, so that in its memorized conformation, the polymer stretchesthe perforations open. At temperatures of greater than 20° C., however,the memory polymer does not conform to its memorized shape, and elastictension of the elastomer pulls the perforations shut.

The inner compartment is filled with pizza, at a local temperature of40° C. As the pizza is transported, the local temperature decrease, andeventually reaches 20° C. When the temperature reaches 20° C., the shapememory polymer switches from its non-memorized conformation (in whichelastic tension of the sheet was sufficient to “pull” the perforationsclosed), to its memorized conformation (in which the tensile force ofthe polymer “pushes” the perforations open). The perforations open,allowing water to flow into the intermediate compartment, and solubilizethe two exothermic reactants, which react exothermically. The exothermicreaction heats the pizza.

The present disclosure is not to be limited in terms of the particularembodiments described in this application, which are intended asillustrations of various aspects. Many modifications and variations canbe made without departing from its spirit and scope, as will be apparentto those skilled in the art. Functionally equivalent methods andapparatuses within the scope of the disclosure, in addition to thoseenumerated herein, will be apparent to those skilled in the art from theforegoing descriptions. Such modifications and variations are intendedto fall within the scope of the appended claims. The present disclosureis to be limited only by the terms of the appended claims, along withthe full scope of equivalents to which such claims are entitled. It isto be understood that this disclosure is not limited to particularmethods, reagents, compounds, compositions or biological systems, whichcan, of course, vary. It is also to be understood that the terminologyused herein is for the purpose of describing particular embodimentsonly, and is not intended to be limiting.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to embodiments containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should be interpreted to mean “at least one”or “one or more”); the same holds true for the use of definite articlesused to introduce claim recitations. In addition, even if a specificnumber of an introduced claim recitation is explicitly recited, thoseskilled in the art will recognize that such recitation should beinterpreted to mean at least the recited number (e.g., the barerecitation of “two recitations,” without other modifiers, means at leasttwo recitations, or two or more recitations). Furthermore, in thoseinstances where a convention analogous to “at least one of A, B, and C,etc.” is used, in general such a construction is intended in the senseone having skill in the art would understand the convention (e.g., “asystem having at least one of A, B, and C” would include but not belimited to systems that have A alone, B alone, C alone, A and Btogether, A and C together, B and C together, and/or A, B, and Ctogether, etc.). In those instances where a convention analogous to “atleast one of A, B, or C, etc.” is used, in general such a constructionis intended in the sense one having skill in the art would understandthe convention (e.g., “a system having at least one of A, B, or C” wouldinclude but not be limited to systems that have A alone, B alone, Calone, A and B together, A and C together, B and C together, and/or A,B, and C together, etc.). It will be further understood by those withinthe art that virtually any disjunctive word and/or phrase presenting twoor more alternative terms, whether in the description, claims, ordrawings, should be understood to contemplate the possibilities ofincluding one of the terms, either of the terms, or both terms. Forexample, the phrase “A or B” will be understood to include thepossibilities of “A” or “B” or “A and B.”

In addition, where features or aspects of the disclosure are describedin terms of Markush groups, those skilled in the art will recognize thatthe disclosure is also thereby described in terms of any individualmember or subgroup of members of the Markush group.

As will be understood by one skilled in the art, for any and allpurposes, such as in terms of providing a written description, allranges disclosed herein also encompass any and all possible subrangesand combinations of subranges thereof. Any listed range can be easilyrecognized as sufficiently describing and enabling the same range beingbroken down into at least equal halves, thirds, quarters, fifths,tenths, etc. As a non-limiting example, each range discussed herein canbe readily broken down into a lower third, middle third and upper third,etc. As will also be understood by one skilled in the art all languagesuch as “up to,” “at least,” and the like include the number recited andrefer to ranges which can be subsequently broken down into subranges asdiscussed above. Finally, as will be understood by one skilled in theart, a range includes each individual member. Thus, for example, a grouphaving 1-3 cells refers to groups having 1, 2, or 3 cells. Similarly, agroup having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells,and so forth.

From the foregoing, it will be appreciated that various embodiments ofthe present disclosure have been described herein for purposes ofillustration, and that various modifications may be made withoutdeparting from the scope and spirit of the present disclosure.Accordingly, the various embodiments disclosed herein are not intendedto be limiting, with the true scope and spirit being indicated by thefollowing claims.

1. A cooling system comprising: a first reactant; a second reactant, wherein the first reactant can endothermically react with the second reactant to absorb heat; and a temperature-responsive divider positioned between at least some of the first reactant and at least some of the second reactant, wherein at a first temperature, the temperature-responsive divider is impermeable to the first reactant, the second reactant, or the first reactant and the second reactant, and wherein at a second temperature, the temperature-responsive divider is permeable to the first reactant, the second reactant, or the first reactant and the second reactant.
 2. The cooling system of claim 1, wherein the first reactant contacts a first side of the temperature-responsive divider, wherein the second reactant contacts a second side of the temperature-responsive divider, and wherein the first side is opposite to the second side of the temperature-responsive divider.
 3. The cooling system of claim 1, wherein the temperature-responsive divider comprises an expandable sheet comprising at least a perforation, wherein the perforation is impermeable to the first reactant and the second reactant when the expandable sheet is in a first conformation, and wherein the perforation is permeable to the first reactant, the second reactant, or the first reactant and the second reactant when the expandable sheet is in a second conformation.
 4. The cooling system of claim 3, wherein the expandable sheet comprises at least one of a rubber, a metal, or an elastomer material.
 5. The cooling system of claim 3, wherein the temperature-responsive divider further comprises at least one temperature-responsive actuator in tensile communication with the expandable sheet, wherein the at least one temperature-responsive actuator is configured to position the sheet in the first conformation at the first temperature, and wherein the at least one temperature-responsive actuator is configured to position the sheet in the second conformation at the second temperature, wherein the second temperature is greater than the first temperature.
 6. The cooling system of claim 5, wherein the at least one temperature-responsive actuator comprises at least one of a bimetal, a shape-memory metal alloy, or a shape memory polymer.
 7. The cooling system of claim 1, wherein the temperature-responsive divider comprises a polymer membrane, wherein at least a portion of a surface of the polymer membrane is hydrophilic at a first temperature, and wherein the portion of the surface of the polymer membrane is hydrophobic at a second temperature, wherein the second temperature is greater than the first temperature.
 8. The cooling system of claim 7, wherein the polymer membrane comprises N-isopropyl acryl amide.
 9. The cooling system of claim 1, wherein the first reactant and the second reactant comprise a first/second reactant pairing comprising at least one of: H₂O/NH₄NO₃, H₂O/NH₄Cl, NH₄NO₃/Urea, H₂O/Urea, H₂O/Ba(NO₃)₂, citric acid/sodium bicarbonate, H₂O/Xylitol, and H₂O/Erythritol.
 10. The cooling system of claim 1, wherein at least one of the first reactant and the second reactant comprises a liquid, a gel, or a liquid and a gel.
 11. The cooling system of claim 1, further comprising: a first compartment configured to contain the first reactant; and a second compartment configured to contain the second reactant, wherein at least a portion of the first compartment is defined by a first surface of the temperature-responsive divider, and wherein at least a portion of the second compartment is defined by a second surface of the temperature-responsive divider.
 12. The cooling system of claim 1, further comprising a storage compartment disposed adjacent to the first reactant, the second reactant, or the first and second reactant.
 13. The cooling system of claim 1, wherein the temperature-responsive divider can change to a configuration that is impermeable to the first reactant, the second reactant, or the first and second reactant upon a return of the temperature-responsive divider to the first temperature.
 14. The cooling system of claim 1, wherein the second temperature is higher than the first temperature.
 15. A method of regulating a temperature, the method comprising: providing a cooling system comprising: a first reactant; a second reactant, wherein the first reactant can react endothermically with the second reactant; and a temperature-responsive divider positioned between at least a part of the first reactant from at least a part of the second reactant; and changing a first conformation of the temperature-responsive divider to a second conformation of the temperature-responsive divider upon an increase in temperature, wherein the second conformation permits the first reactant, the second reactant, or the first and the second reactant to pass through the temperature-responsive divider such that an endothermic reaction occurs.
 16. The method of claim 15, wherein the first conformation effectively separates the first reactant from the second reactant at the first temperature, thereby preventing the first reactant from reacting with the second reactant.
 17. The method of claim 15, the method further comprising changing the second conformation of the temperature-responsive divider to the first conformation upon a decrease in the temperature.
 18. The method of claim 15, wherein the temperature-responsive divider comprises an expandable sheet that comprises at least one perforation, and wherein changing the first conformation of the temperature-responsive divider to the second conformation of the temperature-responsive divider comprises straining the expandable sheet such that the at least one perforation opens.
 19. The method of claim 15, wherein the temperature-responsive divider comprises a bimetal, and wherein changing the first conformation of the temperature-responsive divider to the second conformation of the temperature-responsive divider comprises bending the bimetal.
 20. The method of claim 15, wherein the temperature-responsive divider comprises at least one of a shape-memory alloy or a shape memory polymer, and wherein changing the first conformation of the temperature-responsive divider to the second conformation of the temperature-responsive divider comprises changing a shape of the shape-memory alloy or the shape memory polymer.
 21. The method of claim 15, wherein the temperature-responsive divider comprises a surface of a polymer, and wherein changing the first conformation of the temperature-responsive divider to the second conformation of the temperature-responsive divider comprises changing at least a portion of the surface of the polymer from a hydrophilic state to a hydrophobic state.
 22. The method of claim 15, wherein the increase in local temperature comprises an increase of at least about 5° C.
 23. The method of claim 15, wherein the first reactant and the second reactant comprise a first/second reactant pairing comprising at least one of: H₂O/NH₄NO₃, H₂O/NH₄Cl, NH₄NO₃/Urea, H₂O/Urea, H₂O/Ba(NO₃)₂, citric acid/sodium bicarbonate, H₂O/Xylitol, and H₂O/Erythritol.
 24. A packaging comprising: a first reactant; a second reactant, wherein the first reactant can endothermically react with the second reactant to absorb heat; and a temperature-responsive divider positioned between at least some of the first reactant and at least some of the second reactant, wherein at a first temperature, the temperature-responsive divider is impermeable to the first reactant, the second reactant, or the first reactant and the second reactant, and wherein at a second temperature, the temperature-responsive divider is permeable to the first reactant, the second reactant, or the first reactant and the second reactant.
 25. A method of preparing a cooling system, the method comprising: providing a first reactant; providing a second reactant, wherein the first reactant can endothermically react with the second reactant to absorb heat; and providing a temperature-responsive divider positioned between at least some of the first reactant and at least some of the second reactant, wherein at a first temperature, the temperature-responsive divider is impermeable to the first reactant, the second reactant, or the first reactant and the second reactant, and wherein at a second temperature, the temperature-responsive divider is permeable to the first reactant, the second reactant, or the first reactant and the second reactant. 26-29. (canceled) 